Dredging, targeting the unseen! ...

By Fred Steynberg

Some would consider dredging as far removed from fly fishing as the dassie from the elephant, although they technically belong to the same family there is really not much obvious comparison. Dredging remains however one of the only ways to reach and target non-pelagic fish on shallow reefs.  Many wonderful, powerful and sporty fish are often caught on conventional drop-shot’s and jigging and there is no reason why we fly guys can’t also join in on the fun.

Dredging is by no means a new practise, fly fishermen have done it for many years but it has been a little under the radar because there is a misconception among some that it is not the pure way to fly fish.  I will agree with many when it is said that the ultimate fly fishing experience is the one when the quarry is visible to the angler and the imitative fly is presented with a floating line, in other words, sight fishing.  A fly rodder that has never tried dredging, in my opinion is losing out on a whole different experience and tons of fun.  Personally there is very little that compares to the thrill of the unknown and the challenge to explore it and this is often exactly what dredging, in the right kind of waters, is all about.  You never really, exactly know what your fly is doing down there and neither are you certain what Leviathan will be close and willing enough to smash it.  When fish take a dredged fly down deep it is often a violent act that brings the stripping action to an abrupt stop and sends a thrilling jolt echoing up the fly line, through the rod and straight into the anglers arm.  This is the moment that I look  forward to the most time and time again, but  I  lie if I say that the uncontrollable speeding away of the fish after hook-up, the palming of the reel and the hanging onto the rod for all its worth, is a lesser thrill.

Where to dredge

Dredging in the salt is a little like fishing a fresh water lake for trout, using a sinking line and a fly such as a woolly bugger that attracts the fish’s attention while partly imitating the food source that can be found at a certain depth.  The only difference is that when dredging the deep salt one has to contend with currents, the drift of the boat, and depth often far beyond the capability of any conventional fly lines’ sink rate.  We often target reefs, pinnacles, submerged wrecks and drop-off’s that lie at depths of 6 – 30 meters below the surface.

Different fish species and sizes are found at different depths.  Shallower reefs of 6 – 13m are often more productive during lower light conditions as fish can be spooked by too much sunlight and game fish lose the element of surprise if they are visible.  Reefs and structures at 13 – 20 m can be productive and it is not too difficult to get a heavy line to the bottom quickly at this depth.  At 18 – 25m we often find dredging the most effective.  Large predatory reef dwellers frequent these depths, especially if there is good structure and food.  If these areas are close to a drop-off or underwater cliff then it’s even better as large fish will often attack from the drop-off depth.  The border line areas for fly lines are 28 – 35+ m deep.  Just imagine your fly line that is an average length of 30 – 35m, having to go down to that depth, it will have to be a vertical drop.  This is often possible to achieve, when the wind drift opposes the current drift as illustrated in A (the current flows one way but the wind pushes the boat the other) or when fishing at the lull of the tides in calm weather (low wind) conditions.

The fly line will often take the fly down vertically and when retrieving it is almost like vertical jigging.

The fly does not necessarily need to be dragging right on the bottom.  It is however important to get it down, within the 3-5m zone above the bottom, as close as possible to ensure that the relatively insignificant fly attracts attention.  Various fish species will feed at different depths on and above these hotspots and as the fly is stripped up from the depth it may attract the attention of other pelagic fish that are non- residents (reef fish).   


For example;  in the more central – northern parts of Mozambique, bottom, reef dwellers such as Emperors, Blood Snappers, Boha Snappers, Rock Cods, Grouper,  Yellow Spot Kingfish (among others) hug the reefs or structures and the fly needs to be right down deep for optimal results.  Bluefin Kingfish, Jobfish, Bludger Kingfish and Queenfish ,King Mackeral (to name a few and of which some are semi-reef dwellers and others pelagic) will often intercept the fly a little further up the water column.  In turn Kawa-kawa, Cobia, Yellowfin Tuna, Salad fish, Needlefish generally feed above the structures and a fly may be slammed anywhere from half way down the water column all the way up to the surface (Illustration B) .


Tackle for dredging

 When dredging the most important part of your tackle should be the line as its weight and make-up will determine the depth that one will be able to fish.  In the past full sinking lines were used to achieve depth but they were often difficult to cast and cumbersome on shallower reefs.  Shooting heads or the newer fused sink tip fly lines are less complicated to handle but often rises off the bottom when retrieved because of the running line inability to sink at the same rate as the heavy head or sinking tip.  In turn, full sinking fly lines keep the fly down all the way to the boat and are often a better depth finding option. Shooting sinking heads and sink tip lines are nowadays more fashionable and controllable.

The tip or weighted shooting heads or sinking part of the sink-tip lines should be matched with the rod weight and depth of the reefs or structures that one proposes to fish.  An experienced angler with a good boat handler will be able to effectively fish shallow reefs and drop-offs at  between 6 and 18m with a 300 – 400 grain shooting head (somewhere between 6 – 8+ inches per second sink rate) or sink-tip line.  A 10 – 11 weight rod will be most suitable for these lines and should easily cast when necessary.  A 12 weight rod can also be used if the fish species targeted, such as large GT’S are around and more gun is needed.

500 – 750 Grain (sink rate of 8 – 10’’ +, depending on the line make) shooting heads, sinking tip or full lines is what you need to reach down to hotspots that lie at 18 – 25m.  A competent fly rodder should, without any hassle, be able to cast the 600 grains with a 12w rod, but the heavier, the more difficult it will become and a lobbing action is eventually required to achieve distance.  700 Grain+ lines are so heavy and cumbersome to cast that they are not considered casting lines although it is possible to cast or lob them even though the action is not very attractive.  For these lines 12 – 14w are better suited.  .

Some helpful dredging tips

To aid the fly lines descent when dredging deep hotspots it is often necessary to use weighed flies.  It is however important to understand that the fly should not be designed to drag the fly line down to the required depth but should have only enough weight to not inhibit the fly line descent.  If a fly becomes too heavy to cast then the act of fishing with it cannot really be called fly fishing.

A fly that battles to sink fast enough at certain depths because of the materials used or the absence of weight in the form of lead or weighted eyes, will often slow down the line descent and at times cause the weighted line to spiral around itself when descending, leaving the angler with a bunched up line after the retrieve.

If the drift is slow and the strike zone is not too deep, (6 – 15 m) then the fly should be cast a short distance down current and loose line should be fed to the sinking head so that depth can be achieved. This method would allow the line to be retrieved at an angle once it has reached the correct depth (illustration D).

Drift is almost always going to play a part when dredging and one will constantly need to use methods to counter it in order to reach hotspots.  A way to work the drift in order to allow the line to sink is to cast the fly and line up-current and to feed line as it sinks with the current.  This will buy sinking time and the fly is then retrieved as the line starts pulling down current (illustration C).


It is of primary importance to understand that if you are getting a negative retrieve the chances of catching a half decent fish will be very marginal.  Negative retrieve is achieved by casting up the current (or drift) and stripping back, the fly drifts towards the angler while he retrieves and it is almost impossible (unless the retrieve rate is very high) to relay the desired action through to the fly. It is necessary to always strip the fly back up current when dredging to create a positive action on the fly, thus a positive retrieve.

The speed of a drift is often too fast to effectively dredge and not even the heaviest fly lines can then reach the depth that is required.  I have often measured the drift and have come to a rule of thumb conclusion that if the boat is moving (ground speed) more than 2.8 - 3km + per hour the line merely opens up or lifts up the water column in the direction of the current (or drift) and does not reach the desired depth (illustration E).  It is times like this that an angler should find an alternative method of fishing or alternatively wait for the wind to stop or the current to change, slowing the drift.


I prefer drifting freely over reefs and hotspots so that a larger area can be covered and then repeating the drift a couple of times.  It is however often advisable, if the wind drift is too much, to anchor the boat so that an effective dredge can be achieved.  This method can however be hazardous if the boat handler (skipper) does not have a fair understanding of the area, sea conditions and surface obstacles. 

Retrieval rates often depend on the fish species targeted, the depth that one is dredging at and the speed of the drift and should be varied.  If the drift is slow and deep, then I prefer a slower retrieve for bottom dwellers and often speed up the retrieve, the closer to the boat the fly gets, to attract faster moving pelagic fish that feed closer to the surface.  If the drift is quick and the required depth cannot be reached then a faster, even over-hand retrieve may, in the correct areas, trigger fish such as Yellowfin Tuna, Kawa-kawa, Wahoo, King Mackeral....

It is often necessary to use an imitative fly when dredging over shallower structures in clear water, but the deeper the fly line drags the fly, the less imitative one needs to go.  It is at depths of 15 – 30m where the action, profile, colour and size of the fly is of greater importance than its finer details.

The element of surprise plays as a big a role when dredging that with any other form of fly fishing. Try not rush onto a hotspot with all horses full-throttle but rather slow down before the point of drift and gently manoever the boat into position for the drift. The first drift or down as we call it should be the most productive, fish are still unaware of their pursuit and are happy to jump on a fly.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             

To master dredging many more tricks will have to be learned during hours of hit and miss time on the deep.  I have often fly fished or dredged whilst others on the same boat fish conventionally with jigs and drop-shots.  On the shallower reefs and with favourable currents a competent fly-dredger will compete with the conventional guys and they would marvel at the ease with which the fly-rodders attract different size and species of fish.  To be honest, in retrospect, I have also watched them haul out fish in deeper and less favourable conditions whilst grinding my teeth.  It is then that I dream short dreams about building heavier flies and designing deeper sinking lines but always return to reality by repeating in my mind the words in the ‘Windhoek Lager’ advertisement....just keep it real!